Resistance of high-strength concrete to projectile impact M. H. Zhang and G. Yang Department of Civil Engineering, National University of Singapore, Singapore ABSTRACT: This paper summarizes results from a laboratory experimental study on the resistance of concrete to simulated impact loading of fragments. The impact of fragments was simulated by the impact of ogive-nosed projectiles with a diameter of 12.6mm and a mass of 15 grams traveling at velocities from ~600 to 700 m/s. Effects of fibers, aggregate, curing temperature, compressive and flexural tensile strength of concrete on the impact resistance are evaluated and discussed. The results indicate that the incorporation of a small amount of fibers can reduce the crater diameter effectively as the fibers are able to bridge cracks and to hold concrete together. However, in order to reduce the penetration depth, reduced water-to-cement ratio and increased strength of the concrete matrix are required. Nevertheless, when the strength was beyond a certain level, further increase in the compressive strength did not reduce the penetration depth. Strong aggregate with bigger sizes seems to be beneficial to improve the impact resistance so long as the workability is satisfactory and the aggregate sizes meet requirements based on the size of structural members and the spacing between reinforcing bars and spacing between reinforcing bar and form.